Mold protector

ABSTRACT

A safety mechanism for a molding machine in the form of a twopart pressure sensitive means, a first part being the movable platen and a second part being disposed forwardly thereof and supporting its mold with a gap of predetermined dimension being provided between the parts by means of friction free reeds supporting the second part relative to the first part so arranged that, in the event of a malfunction or in the presence of an obstruction, the pressure created on the mold creates a closing of the gap and triggers micro switches which are tied in with the machine opening and closing mechanism to quickly reverse the closing action of the molding machine.

nitc States atent n 1 Broderick I l I 3,757,679

[451 Sept. 11, 1973 MOLD PROTECTOR 22 Filed: Nov. 26, 1971 211 Appl.No.: 202,116

Primary Examiner-Billy J. Wilhite Att0rney-Kenwood Ross et al.

[57] ABSTRACT A safety mechanism for a molding machine in the form of atwo-part pressure sensitive means, a first part being the movable platenand a second part being disposed forwardly thereof and supporting itsmold with a gap of predetermined dimension being provided between theparts by means of friction free reeds supporting the second partrelative to the first part so arranged that, in the event of amalfunction or in the presence of an obstruction, the pressure createdon the mold creates a closing of the gap and triggers micro switcheswhich are tied in with the machine opening and closing mechanism toquickly reverse the closing action of the molding machine.

1 Claim, 3 Drawing Figures Patented Sept. 11, 1973 2 Sheets-Sheet 1 FIG.

Patented Sept. 11, 1973 2 Sheets-Sheet 2 //I////// IIIIIII/III/IIIIIIFIG. 3.

INVENTOR. WALTER M. anoosmcx BY 15mm @014 85mm 5 2mm ATTORNEYS.

'MOILD PROTECTOR The invention relates to protective arrangements orsafety devices adapted for the protection of personnel and of the toolsemployed with molding machines or presses.

In molding machines or presses, the working elements are frequently madein at least two parts, one of which can slide in relation to the frameof the machine and come into confrontation with the other part along aclosing plane in manner such as to form a sealed cavity (in the case ofa molding machine) or a forming area (in the case of a press) so thatthe molding or pressing may be effected. When there is a foreign body inthis closing plane, on the one hand the desired sealing is not realizedso as deleteriously to effect the workpiece, and

on the other hand there is a risk that the foreign body may seriouslydamage the machine;

The invention provides arrangements for avoiding these dangers andrisks.

According to the invention, there is provided a protective arrangementin a machine in which parts are moved together to close the machine andlimiting means comprising first contact means arranged to be actuatedwhen, and only when, the mold parts are satisfactorily closed and secondcontact means arranged to be actuated when the closed mold has beendisplaced to a predetermined extent, said first and second contact meanshaving contacts in an electrical circuit for controlling the followingof an operational cycle arranged in such a manner that upon actuation ofsaid second contact means, if said first contact means has notpreviously been actuated in the current operational cycle, said controlcircuit interrupts the movement of the mold and produces return movementof the mold.

The invention provides a safety device for a mold machine or a presswhich is operative to automatically withdraw one of the work-formingmembers of the machine from its normal operative position in the eventthat there is an obstruction in the path of relative movement of thatmember. In other words, if the operator inadvertently puts his handbetween the work-forming members ofthe machine during an operatingcycle, the safety device of this invention is designed automatically toreverse the closing direction of movement of the movable platen and itssupported work-forming member so that the machine is motivated intomachine opening direction so that the handwill not be injured.

Of course, the obstruction might be something other than the operatorshand and might simply be such as a projecting portion of an improperlypositioned mold part.

In the drawings:

FIG. 1 is a view, in side elevation, of the apparatus of the inventionin combination with other pprtinent parts of the mold or press;

FIG. 2 is a fragmentary view, in front elevation,.of the upper portionof the inboard pressure sensitive pad and related upper tie bars lookingin the direction of the arrow a in FIG. 1 with the associated mold partremoved; and 7 FIG. 3 is a fragmentary view, in perspective, of theapparatus shown in FIG. I with the support arms and rollers and tie barsremoved.

The usual mold or press comprehends a stationary platen l and a movableplaten l2 movable toward and away from the stationary platen alongconventional sets of upper and lower tie bars 14 by virtue of such asball sleeves 116 on opposite sides of the machine (not shown). Thesliding of the movable platen is controlled by conventional means, forexample, a hydraulicallyoperated ram 18.

Movable platen 12 will be understood to serve the function of supportingthe so-called inboard pressure sensitive pad, as will appear.

An inboard pressure sensitive pad 20 is disposed adjacent the face ofthe movable platen 12 facing stationary platen Ill and is looselysecured to the movable platen as by shoulder screw retainers 22 fixed tothe movable platen and extendable through enlarged bores 24 and seats 26through the inboard pressure sensitive pad and adjustable so as to limitthe dimension of the gap G between members 112 and 20 from exceeding acertain predetermined and adjustable dimension.

The forward face of movable platen 12 is provided with a plurality ofspaced vertical recesses 30, (see FIG. 3) extending from the top to thebottom thereof, in each of which recesses a reed or flat elongate spring32 is receivable in a friction free manner and each being fixed at itsupper extremity to the movable platen as by suitable bolting 34 and eachbeing fixed at its lower extremity in a complimental recess 35 in therearward face of inboard pressure sensitive pad 20 and secured theretoas by bolting 36.

Extending upwardly from the upper portion of each side edge of inboardpressure sensitive pad 20 is a supportarm 4i) suitably secured to thesaid pad as by bolting and configured so as to define an uppermosthorizontally extending web portion which overlies the respective tie bar14 in a direction toward the stationary platen and mounting a roller oroilite pad 42 at itsfree extremity, which roller or pad rides on theupper surface of the tie bar in manner such as to accept the load of theweight of the inboard pressure sensitive pad.

Thus, inboard pressure sensitive pad 20 is mounted on movable platen l2by friction free reeds 32 and the weight of the said pad is carried bythe support arms 40 bearing on their respective tie bars 14 through themeans of the rollers 42.

On opposite sides of the machine, balance springs 44 seat against themovable platen, extend forwardly through suitable openings in inboardpressure sensitive pad 26), and seat at their opposite ends within arespective housing 46 secured to the forward face of said pad.

Adjusting means 45 extend through each housing and are held in adjustedposition with respect to balance springs 44 by means of adjusting nuts50.

By the adjustment of the balance springs, the inboard pressure sensitivepad and movable platen may be brought into equilibrium so that a smallexternal force will compress the springs and signal go" and no goconditions.

With a go condition, a provided first limit switch 52 or stationaryplaten Ill makes before a second limit switch 54 on movable platen 12 soas to indicate a safe condition wherefore the machine is in conditionfor lock up.

With a no go condition, second limit switch 54 makes before first limitswitch 52 so as to indicate an unsafe condition and to effect a reversalof the operation of ram lb into opening movement.

In the case of a molding machine, a mold part is secured to stationaryplaten W by any conventional means and a mold part (62 is secured toinboard pressure sensitive pad 20 on movable platen 12.

By the construction described, the inboard pressure sensitive pad isseen to float relative to the movable platen so as to allow readydeflection upon encountering any obstruction or misalignment in the workarea which deflection will cause the movable platen to change itsmovement from a closing movement to an opening movement.

I claim:

1. In a mold or press closing protective device of a molding machinehaving oppositely-facing fixed and movable platens and driving means forselectively motivating the movable platen toward and away from the fixedplaten along sets of upper and lower tie bars, the improvement in acontrol circuit for precluding the closing of the fixed and movableplatens when a foreign body is present between the platens bycontrolling the moving portions of the molding machine which are movingin mold-closing direction to actuate electromechanical reversing meansand including:

a pressure-sensing plate floatingly-mounted relative to and forwardly ofthe confronting face of the movable platen,

limit means for precluding the gap between the plate and movable platenfrom exceeding a predetermined dimension,

the movable platen being provided with a plurality of recesses extendingfrom the top to the bottom of the confronting face thereof,

a plurality of yieldable elongated reeds each nestably received within arespective one of the recesses of the movable platen and fixedly mountedat one end to an adjacent portion of the movable platen and at anopposite end to an adjacent portion of the non-confronting face of theplate,

support arms each secured to the plate and having a web portion mountinga roller for riding along a respective upper tie bar, and

control means including micro-switches mounted on the movable andstationary platens,

the switch on the movable platen being operative in response to movementof the pressure-sensing plate on encountering an obstruction between theplatens for reversing the direction of movement of the movable platen.

1. In a mold or press closing protective device of a molding machine having oppositely-facing fixed and movable platens and driving means for selectively motivating the movable platen toward and away from the fixed platen along sets of upper and lower tie bars, the improvement in a control circuit for precluding the closing of the fixed and movable platens when a foreign body is present between the platens by controlling the moving portions of the molding machine which are moving in moldclosing direction to actuate electromechanical reversing means and including: a pressure-sensing plate floatingly-mounted relative to and forwardly of the confronting face of the movable platen, limit means for precluding the gap between the plate and movable platen from exceeding a predetermined dimension, the movable platen being provided with a plurality of recesses extending from the top to the bottom of the confronting face thereof, a plurality of yieldable elongated reeds each nestably received within a respective one of the recesses of the movable platen and fixedly mounted at one end to an adjacent portion of the movable platen and at an opposite end to an adjacent portion of the non-confronting face of the plate, support arms each secured to the plate and having a web portion mounting a roller for riding along a respective upper tie bar, and control means including micro-switches mounted on the movable and stationary platens, the switch on the movable platen being operative in response to movement of the pressure-sensing plate on encountering an obstruction between the platens for reversing the direction of movement of the movable platen. 